“Shaped” data may be used during testing of a storage device. For example, the storage device may be programmed using data having different shaping levels (e.g., different ratios of 1s to 0s) to test the performance of the storage device. One way of generating shaped data is to use a parallel random number generator. The parallel random number generator may generate a sequence of multiple bits in parallel, where each bit has a 50% chance of being a 0 and a 50% chance of being a 1. The randomly generated bit sequence may then be used to generate the shaped bits, for example, by changing certain bits of the bit sequence from 0 to 1, or vice versa.